Intranuclear targeting of AML/CBFalpha regulatory factors to nuclear matrix-associated transcriptional domains.
The AML/CBFalpha runt transcription factors are key regulators of hematopoietic and bone tissue-specific gene expression. These factors contain a 31-amino acid nuclear matrix targeting signal that supports association with the nuclear matrix. We determined that the AML/CBFalpha factors must bind to the nuclear matrix to exert control of transcription. Fusing the nuclear matrix targeting signal to the GAL4 DNA binding domain transactivates a genomically integrated GAL4 responsive reporter gene. These data suggest that AML/CBFalpha must associate with the nuclear matrix to effect transcription. We used fluorescence labeling of epitope-tagged AML-1B (CBFA2) to show it colocalizes with a subset of hyperphosphorylated RNA polymerase II molecules concentrated in foci and linked to the nuclear matrix. This association of AML-1B with RNA polymerase II requires active transcription and a functional DNA binding domain. The nuclear matrix domains that contain AML-1B are distinct from SC35 RNA processing domains. Our results suggest two of the requirements for AML-dependent transcription initiation by RNA polymerase II are association of AML-1B with the nuclear matrix together with specific binding of AML to gene promoters.
Zeng
C
C
Department of Cell Biology and Cancer Center, University of Massachusetts Medical Center, 55 Lake Avenue North, Worcester, MA 01655, USA.
McNeil
S
S
Pockwinse
S
S
Nickerson
J
J
Shopland
L
L
Lawrence
J B
JB
Penman
S
S
Hiebert
S
S
Lian
J B
JB
van Wijnen
A J
AJ
Stein
J L
JL
Stein
G S
GS
D002451:Cell Compartmentation; D050676:Core Binding Factor Alpha 2 Subunit; D004268:DNA-Binding Proteins; D006367:HeLa Cells; D006801:Humans; D008856:Microscopy, Fluorescence; D015530:Nuclear Matrix / Q000378:metabolism*; D011518:Proto-Oncogene Proteins; D012319:RNA Polymerase II / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection
D050676:Core Binding Factor Alpha 2 Subunit; D004268:DNA-Binding Proteins; D011518:Proto-Oncogene Proteins; C493728:RUNX1 protein, human; D014157:Transcription Factors; D012319:RNA Polymerase II